Examples of current and recent research projects
Long-term dynamics of wading bird populations as indicators of ecological change.
Using a combination of extensive and intensive monitoring techniques, the Frederick lab with partners at South Florida Water Management District, Florida Atlantic University, Everglades National Park and Audubon of Florida has systematically monitored nesting by wading birds during the past 30 years in 3,300 km2 of the Everglades. This work has included studies of reproductive success, energetics, nutrient cycling, foraging ecology, and contamination. When combined with a rich historical record of nesting, the resulting database provides a rare glimpse at how wading bird populations have changed in size, location, timing and success as a result of anthropogenic change in the hydrology of the Everglades. The results have helped understand the historical hydrological functioning of the ecosystem, and have been used to design and modify plans for restoring the Everglades ecosystem. (Peter Frederick and nearly all past students)
- Predicting nest success from hydrological data
- Severe droughts are linked with exceptionally large nesting events
- How wading bird populations can be used as an indicator of restoration success
- Monitoring bird populations over large areas
- Use of the superpopulation approach to estimate colony size over time
Consequences of methylmercury contamination on wading bird reproduction and survival.
We have used both natural and manipulative exposure experiments to examine the effects of methylmercury on avian reproduction, using the Everglades as a study example. Taken together, the results indicate that even very low, chronic exposure to methymercury can have important sublethal effects on appetite, immune function, reproduction, and survival. Experimental work indicates that low, environmentally relevant MeHg exposure can affect endocrine function to the extent that male-male pairings are significantly increased. The net result of these effects suggests that an area as contaminated as the Everglades may become a regional demographic sink for aquatic birds. While much of the mercury effect on avian reproduction has been assumed to come from developmental effects, our work now suggests that at low, chronic exposure, parental behavior may be the main process affected. (Evan Adams, Nilmini Jayasena, Ignacio Rodriquez, Peter Frederick)
- Effects of MeHg on egret physiology and immune function
- 100-year history of avian mercury contamination using museum specimens
- Exposure levels for fish eating birds in south Florida
- The Everglades mercury story and management for other wetlands
- MeHg-mediated endocrine disruption in ibises
- MeHg exposure linked to population decline in ibises
- Mate choice and MeHg exposure
Demography and movements of Wood Storks (Mycteria americana).
We have used satellite data from several hundreds of birds to to understand regional and seasonal movements, habitat use, and survival of Wood Storks. This species moves widely in response to hydrologic change and food availability in the southeastern US. Working with a consortium of biologists throughout the range, we have gathered enough rangewide survival and reproductive success information to construct the first demographic models for this species. (Rena Borkhataria, Becky Hylton, Noah Burrell, Simona Picardi, Peter Frederick, Mathieu Basille)
- Demographic model for the Wood Stork
- Nestling health and postfledging survival of Wood Storks
- Movements of storks in relation to regional hydrology
Colony longevity as an indicator of habitat quality.
Wood Storks are important wetland indicators and are listed as Endangered in the southeastern United States, however, the information available for identifying and prioritizing stork colony and feeding habitat are limited and dated. We aim to compare attributes of Wood Stork habitat colonies (e.g., vegetation, physiographic, land use and hydrologic characteristics) that lasted many years, with those that winked out after only a few years, as a way to identify high priority colony characteristics in a survival analysis framework. Using a 39-year record of colonies, our goal is to make the resulting information and tools directly usable by permitting, conservation and land planning agencies, and NGOs. (Ross Tsai, Peter Frederick).
Please see http://www.wec.ufl.edu/faculty/frederickp/woodstork/ for database information.
Effects of fire on nutrient flow and aquatic community organization.
Fire is an historic component of the Everglades, of natural and anthropogenic origin. Typically, fire occurs at the start of the rainy season, May, however recent fire management in many parts of the Everglades includes prescribed fire during December-April, the dry season. Numerous fire managers have reported concentrations of wading birds present in prescribed burn areas immediately after fires and sometimes for weeks afterwards. While it is known that fires release nutrients, it is unclear that nutrients are the mechanism by which wading birds are attracted to burned areas. (Louiise Venne and Peter Frederick)
- Effects of fire on distribution of foraging wading birds
- Effects of fire on productivity of wetland fishes
Food for protection - Ecological facilitation between alligators and breeding long-legged wading birds.
Ecological facilitation is increasingly seen as an important force structuring ecological communities and while most examples come from the plant world, animal communities may also be structured by facilitative interactions. We have focused on an apparent mutualism involving alligators which act to protect nesting long-legged wading birds from mammalian predators. The birds prefer to nest over alligators, both in surveys of unmanipulated populations, and in experimental manipulations using decoys. In addition, the alligators have access to abundant food in the form of starving chicks that drop from nests. Alligators within bird nesting colonies are in significantly better body condition than those not in colonies, suggesting that the benefit may extend to fecundity and survival for alligators. This relationship is likely to be typical of waterbird colonies and crocodilians around the world, and preserving this relationship may have conservation value for both groups. (Lucas Nell, Brittany Burtner, Kwanmok Kim, Peter Frederick )
- Wading birds prefer to nest over alligators
- Alligators have access to abundant food within wading bird colonies
- Association with bird colonies leads to better body condition in alligators.
Oyster reef restoration – engineering estuaries for resilience
Oyster reefs offer some of the most substantial and quantifiable ecosystem services of any organism in the world, but oyster reef communities are probably the most endangered marine community globally. On the Big Bend coast of Florida, we have demonstrated that reefs have declined by over 88% in 30 yr, largely due to decreased freshwater flows to the coast. This creates a feedback loop, because intact reef chains are also responsible for detaining freshwater near the coast and buffering estuarine salinities- reef degradation and salinization of estuaries are therefore strongly linked. Through the use of durable substrate, we are working to restore entire chains of reefs, with the prediction that estuarine communities will be buffered both from wave action and from salinity swings. (Bill Pine, Leslie Sturmer, David Kaplan, Maitane Olabarietta, Christine Angelini, Arnoldo Valle-Levinson)
- Oyster reefs have declined rapidly in less than 30 yr.
- Reef recolonization is limited by substrate, not larval supply
- Offshore reefs serve to buffer estuarine salinities by detaining fresh water
- Offshore reefs are a critical habitat for roosting American Oystercatchers
Effects of a novel predator on avian reproduction
The Burmese Python (Python bivitattus) is now a widespread exotic pest in south Florida, and is practically ubiquitous in the Everglades. This species has been associated with a 95% reduction in small and meso-mammal populations, and commonly eats wetland birds. It is unclear what threat it may pose to large breeding populations of wading birds, but they have been sighted in breeding colonies on several occasions. We are using camera traps to estimate potential predation at nests, and in collaboration with Maggie Hunter of USGS, we are using environmental DNA samples to estimate the distribution of pythons relative to bird breeding sites. (Sophie Orzechowski, Maggie Hunter, Peter Frederick).
- Effects of pythons on reproduction of Great Egrets (ongoing)
- Distribution of invasive pythons relative to bird rookeries in the Everglades (ongoing).